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<div>You are a helpful software engineer assistant.

## Tools
You have access to the following tools:

### bash
Description: Run commands in a bash shell
* When invoking this tool, the contents of the &quot;command&quot; parameter does NOT need to be XML-escaped.
* You don&#x27;t have access to the internet via this tool.
* You do have access to a mirror of common linux and python packages via apt and pip.
* State is persistent across command calls and discussions with the user.
* To inspect a particular line range of a file, e.g. lines 10-25, try &#x27;sed -n 10,25p /path/to/the/file&#x27;.
* Please avoid commands that may produce a very large amount of output.
* Please run long lived commands in the background, e.g. &#x27;sleep 10 &amp;&#x27; or start a server in the background.

Parameters: {&quot;title&quot;: &quot;BashInput&quot;, &quot;type&quot;: &quot;object&quot;, &quot;properties&quot;: {&quot;command&quot;: {&quot;title&quot;: &quot;Command&quot;, &quot;description&quot;: &quot;The bash command to run. Relative path is preferred in the command.&quot;, &quot;type&quot;: &quot;string&quot;}}, &quot;required&quot;: [&quot;command&quot;], &quot;additionalProperties&quot;: false}

### str_replace_editor
Description: Custom editing tool for viewing, creating and editing files
* State is persistent across command calls and discussions with the user
* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep
* The `create` command cannot be used if the specified `path` already exists as a file
* If a `command` generates a long output, it will be truncated and marked with `&lt;response clipped&gt;`

Notes for using the `str_replace` command:
* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!
* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique
* The `new_str` parameter should contain the edited lines that should replace the `old_str`

Parameters: {&quot;title&quot;: &quot;SweEditorInput&quot;, &quot;type&quot;: &quot;object&quot;, &quot;properties&quot;: {&quot;command&quot;: {&quot;title&quot;: &quot;Command&quot;, &quot;description&quot;: &quot;The commands to run. Allowed options are: `view`, `create`, `str_replace`, `insert`.&quot;, &quot;enum&quot;: [&quot;view&quot;, &quot;create&quot;, &quot;str_replace&quot;, &quot;insert&quot;], &quot;type&quot;: &quot;string&quot;}, &quot;path&quot;: {&quot;title&quot;: &quot;Path&quot;, &quot;description&quot;: &quot;Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`.&quot;, &quot;type&quot;: &quot;string&quot;}, &quot;file_text&quot;: {&quot;title&quot;: &quot;File Text&quot;, &quot;description&quot;: &quot;Required parameter of `create` command, with the content of the file to be created.&quot;, &quot;type&quot;: &quot;string&quot;}, &quot;insert_line&quot;: {&quot;title&quot;: &quot;Insert Line&quot;, &quot;description&quot;: &quot;Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`.&quot;, &quot;type&quot;: &quot;integer&quot;}, &quot;new_str&quot;: {&quot;title&quot;: &quot;New Str&quot;, &quot;description&quot;: &quot;Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert.&quot;, &quot;type&quot;: &quot;string&quot;}, &quot;old_str&quot;: {&quot;title&quot;: &quot;Old Str&quot;, &quot;description&quot;: &quot;Required parameter of `str_replace` command containing the string in `path` to replace.&quot;, &quot;type&quot;: &quot;string&quot;}, &quot;view_range&quot;: {&quot;title&quot;: &quot;View Range&quot;, &quot;description&quot;: &quot;Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.&quot;, &quot;type&quot;: &quot;array&quot;, &quot;items&quot;: {&quot;type&quot;: &quot;integer&quot;}}}, &quot;required&quot;: [&quot;command&quot;, &quot;path&quot;], &quot;additionalProperties&quot;: false}

IMPORTANT: ALWAYS adhere to this exact format for tool use:
<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>tool_call_name<span class="token green">&lt;｜tool▁sep｜&gt;</span>tool_call_arguments<span class="token green">&lt;｜tool▁call▁end｜&gt;</span>{additional_tool_calls}<span class="token green">&lt;｜tool▁calls▁end｜&gt;</span>

Where:
- `tool_call_name` must be an exact match to one of the available tools
- `tool_call_arguments` must be valid JSON that strictly follows the tool&#x27;s Parameters Schema
- For multiple tool calls, chain them directly without separators or spaces<span class="token yellow">&lt;｜User｜&gt;</span>&lt;uploaded_files&gt;
/testbed
&lt;/uploaded_files&gt;
I&#x27;ve uploaded a code repository in the directory /testbed (not in /tmp/inputs). Consider the following PR description:

&lt;pr_description&gt;
Bug in posix implementation of django/core/files/locks.py
Description

The posix version of locks (the version which supports import fcntl) has a bug. The code attempts to return True to indicate success or failure acquiring a lock, but instead it always returns False. The reason is that cpython fcntl module returns None if successful, and raises an OSError to indicate failure (see https://docs.python.org/3/library/fcntl.html#fcntl.flock).
Anyone interested in using the non-blocking (i.e. locks.LOCKS_NB) requires a valid return value to know if they have successfully acquired the lock.
I believe the correct implementation should be the following:
diff --git a/django/core/files/locks.py b/django/core/files/locks.py
index c46b00b905..4938347ea7 100644
--- a/django/core/files/locks.py
+++ b/django/core/files/locks.py
@@ -107,9 +107,15 @@ else:
			 return True
	 else:
		 def lock(f, flags):
-			ret = fcntl.flock(_fd(f), flags)
-			return ret == 0
+			try:
+				fcntl.flock(_fd(f), flags)
+				return True
+			except OSError:
+				return False
		 def unlock(f):
-			ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
-			return ret == 0
+			try:
+				fcntl.flock(_fd(f), fcntl.LOCK_UN)
+				return True
+			except OSError:
+				return False

&lt;/pr_description&gt;

Can you help me implement the necessary changes to the repository so that the requirements specified in the &lt;pr_description&gt; are met?
I&#x27;ve already taken care of all changes to any of the test files described in the &lt;pr_description&gt;. This means you DON&#x27;T have to modify the testing logic or any of the tests in any way!

Your task is to make the minimal changes to non-tests files in the /testbed directory to ensure the &lt;pr_description&gt; is satisfied.

You are only allowed to call **ONE** function each time!<span class="token yellow">&lt;｜Assistant｜&gt;</span><span class="token red">&lt;/think&gt;</span>I&#x27;ll help you implement the necessary changes to fix the bug in the posix implementation of `django/core/files/locks.py`. Let me start by examining the current state of the file.<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>str_replace_editor<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;view&quot;, &quot;path&quot;: &quot;/testbed/django/core/files/locks.py&quot;}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span>Here&#x27;s the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 116 lines):
     1	&quot;&quot;&quot;
     2	Portable file locking utilities.
     3	
     4	Based partially on an example by Jonathan Feignberg in the Python
     5	Cookbook [1] (licensed under the Python Software License) and a ctypes port by
     6	Anatoly Techtonik for Roundup [2] (license [3]).
     7	
     8	[1] http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203
     9	[2] https://sourceforge.net/p/roundup/code/ci/default/tree/roundup/backends/portalocker.py
    10	[3] https://sourceforge.net/p/roundup/code/ci/default/tree/COPYING.txt
    11	
    12	Example Usage::
    13	
    14	    &gt;&gt;&gt; from django.core.files import locks
    15	    &gt;&gt;&gt; with open(&#x27;./file&#x27;, &#x27;wb&#x27;) as f:
    16	    ...     locks.lock(f, locks.LOCK_EX)
    17	    ...     f.write(&#x27;Django&#x27;)
    18	&quot;&quot;&quot;
    19	import os
    20	
    21	__all__ = (&#x27;LOCK_EX&#x27;, &#x27;LOCK_SH&#x27;, &#x27;LOCK_NB&#x27;, &#x27;lock&#x27;, &#x27;unlock&#x27;)
    22	
    23	
    24	def _fd(f):
    25	    &quot;&quot;&quot;Get a filedescriptor from something which could be a file or an fd.&quot;&quot;&quot;
    26	    return f.fileno() if hasattr(f, &#x27;fileno&#x27;) else f
    27	
    28	
    29	if os.name == &#x27;nt&#x27;:
    30	    import msvcrt
    31	    from ctypes import (
    32	        POINTER, Structure, Union, byref, c_int64, c_ulong, c_void_p, sizeof,
    33	        windll,
    34	    )
    35	    from ctypes.wintypes import BOOL, DWORD, HANDLE
    36	
    37	    LOCK_SH = 0  # the default
    38	    LOCK_NB = 0x1  # LOCKFILE_FAIL_IMMEDIATELY
    39	    LOCK_EX = 0x2  # LOCKFILE_EXCLUSIVE_LOCK
    40	
    41	    # --- Adapted from the pyserial project ---
    42	    # detect size of ULONG_PTR
    43	    if sizeof(c_ulong) != sizeof(c_void_p):
    44	        ULONG_PTR = c_int64
    45	    else:
    46	        ULONG_PTR = c_ulong
    47	    PVOID = c_void_p
    48	
    49	    # --- Union inside Structure by stackoverflow:3480240 ---
    50	    class _OFFSET(Structure):
    51	        _fields_ = [
    52	            (&#x27;Offset&#x27;, DWORD),
    53	            (&#x27;OffsetHigh&#x27;, DWORD)]
    54	
    55	    class _OFFSET_UNION(Union):
    56	        _anonymous_ = [&#x27;_offset&#x27;]
    57	        _fields_ = [
    58	            (&#x27;_offset&#x27;, _OFFSET),
    59	            (&#x27;Pointer&#x27;, PVOID)]
    60	
    61	    class OVERLAPPED(Structure):
    62	        _anonymous_ = [&#x27;_offset_union&#x27;]
    63	        _fields_ = [
    64	            (&#x27;Internal&#x27;, ULONG_PTR),
    65	            (&#x27;InternalHigh&#x27;, ULONG_PTR),
    66	            (&#x27;_offset_union&#x27;, _OFFSET_UNION),
    67	            (&#x27;hEvent&#x27;, HANDLE)]
    68	
    69	    LPOVERLAPPED = POINTER(OVERLAPPED)
    70	
    71	    # --- Define function prototypes for extra safety ---
    72	    LockFileEx = windll.kernel32.LockFileEx
    73	    LockFileEx.restype = BOOL
    74	    LockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, DWORD, LPOVERLAPPED]
    75	    UnlockFileEx = windll.kernel32.UnlockFileEx
    76	    UnlockFileEx.restype = BOOL
    77	    UnlockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, LPOVERLAPPED]
    78	
    79	    def lock(f, flags):
    80	        hfile = msvcrt.get_osfhandle(_fd(f))
    81	        overlapped = OVERLAPPED()
    82	        ret = LockFileEx(hfile, flags, 0, 0, 0xFFFF0000, byref(overlapped))
    83	        return bool(ret)
    84	
    85	    def unlock(f):
    86	        hfile = msvcrt.get_osfhandle(_fd(f))
    87	        overlapped = OVERLAPPED()
    88	        ret = UnlockFileEx(hfile, 0, 0, 0xFFFF0000, byref(overlapped))
    89	        return bool(ret)
    90	else:
    91	    try:
    92	        import fcntl
    93	        LOCK_SH = fcntl.LOCK_SH  # shared lock
    94	        LOCK_NB = fcntl.LOCK_NB  # non-blocking
    95	        LOCK_EX = fcntl.LOCK_EX
    96	    except (ImportError, AttributeError):
    97	        # File locking is not supported.
    98	        LOCK_EX = LOCK_SH = LOCK_NB = 0
    99	
   100	        # Dummy functions that don&#x27;t do anything.
   101	        def lock(f, flags):
   102	            # File is not locked
   103	            return False
   104	
   105	        def unlock(f):
   106	            # File is unlocked
   107	            return True
   108	    else:
   109	        def lock(f, flags):
   110	            ret = fcntl.flock(_fd(f), flags)
   111	            return ret == 0
   112	
   113	        def unlock(f):
   114	            ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
   115	            return ret == 0
   116	
<span class="token green">&lt;｜tool▁output▁end｜&gt;</span>Now I can see the issue. Looking at the current implementation in lines 109-115, the code is trying to compare the return value of `fcntl.flock()` with 0, but according to the PR description, `fcntl.flock()` returns `None` on success and raises an `OSError` on failure. This means the current implementation will always return `False` because `None == 0` is `False`.

Let me examine the specific lines that need to be changed:<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>str_replace_editor<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;view&quot;, &quot;path&quot;: &quot;/testbed/django/core/files/locks.py&quot;, &quot;view_range&quot;: [109,116]}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span>Here&#x27;s the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 116 lines) with view_range=[109, 116]:
   109	        def lock(f, flags):
   110	            ret = fcntl.flock(_fd(f), flags)
   111	            return ret == 0
   112	
   113	        def unlock(f):
   114	            ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
   115	            return ret == 0
   116	
<span class="token green">&lt;｜tool▁output▁end｜&gt;</span>Now I&#x27;ll implement the fix as described in the PR description. The fix should wrap the `fcntl.flock()` calls in try-except blocks, returning `True` on success and `False` on `OSError`:<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>str_replace_editor<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;str_replace&quot;, &quot;path&quot;: &quot;/testbed/django/core/files/locks.py&quot;, &quot;old_str&quot;: &quot;        def lock(f, flags):\n            ret = fcntl.flock(_fd(f), flags)\n            return ret == 0\n\n        def unlock(f):\n            ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)\n            return ret == 0&quot;, &quot;new_str&quot;: &quot;        def lock(f, flags):\n            try:\n                fcntl.flock(_fd(f), flags)\n                return True\n            except OSError:\n                return False\n\n        def unlock(f):\n            try:\n                fcntl.flock(_fd(f), fcntl.LOCK_UN)\n                return True\n            except OSError:\n                return False&quot;}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span>The file /testbed/django/core/files/locks.py has been edited successfully.<span class="token green">&lt;｜tool▁output▁end｜&gt;</span>Let me verify the changes by viewing the modified section:<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>str_replace_editor<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;view&quot;, &quot;path&quot;: &quot;/testbed/django/core/files/locks.py&quot;, &quot;view_range&quot;: [109,116]}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span>Here&#x27;s the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 122 lines) with view_range=[109, 116]:
   109	        def lock(f, flags):
   110	            try:
   111	                fcntl.flock(_fd(f), flags)
   112	                return True
   113	            except OSError:
   114	                return False
   115	
   116	        def unlock(f):
<span class="token green">&lt;｜tool▁output▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>str_replace_editor<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;view&quot;, &quot;path&quot;: &quot;/testbed/django/core/files/locks.py&quot;, &quot;view_range&quot;: [116,122]}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span>Here&#x27;s the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 122 lines) with view_range=[116, 122]:
   116	        def unlock(f):
   117	            try:
   118	                fcntl.flock(_fd(f), fcntl.LOCK_UN)
   119	                return True
   120	            except OSError:
   121	                return False
   122	
<span class="token green">&lt;｜tool▁output▁end｜&gt;</span>Perfect! The changes have been successfully implemented. Let me verify the complete file structure to ensure everything looks correct:<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>str_replace_editor<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;view&quot;, &quot;path&quot;: &quot;/testbed/django/core/files/locks.py&quot;, &quot;view_range&quot;: [90,122]}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span>Here&#x27;s the content of /testbed/django/core/files/locks.py with line numbers (which has a total of 122 lines) with view_range=[90, 122]:
    90	else:
    91	    try:
    92	        import fcntl
    93	        LOCK_SH = fcntl.LOCK_SH  # shared lock
    94	        LOCK_NB = fcntl.LOCK_NB  # non-blocking
    95	        LOCK_EX = fcntl.LOCK_EX
    96	    except (ImportError, AttributeError):
    97	        # File locking is not supported.
    98	        LOCK_EX = LOCK_SH = LOCK_NB = 0
    99	
   100	        # Dummy functions that don&#x27;t do anything.
   101	        def lock(f, flags):
   102	            # File is not locked
   103	            return False
   104	
   105	        def unlock(f):
   106	            # File is unlocked
   107	            return True
   108	    else:
   109	        def lock(f, flags):
   110	            try:
   111	                fcntl.flock(_fd(f), flags)
   112	                return True
   113	            except OSError:
   114	                return False
   115	
   116	        def unlock(f):
   117	            try:
   118	                fcntl.flock(_fd(f), fcntl.LOCK_UN)
   119	                return True
   120	            except OSError:
   121	                return False
   122	
<span class="token green">&lt;｜tool▁output▁end｜&gt;</span>Excellent! The changes have been successfully implemented. Let me run a quick test to make sure the file is syntactically correct:<span class="token green">&lt;｜tool▁calls▁begin｜&gt;</span><span class="token green">&lt;｜tool▁call▁begin｜&gt;</span>bash<span class="token green">&lt;｜tool▁sep｜&gt;</span>{&quot;command&quot;: &quot;cd /testbed &amp;&amp; python -m py_compile django/core/files/locks.py&quot;}<span class="token green">&lt;｜tool▁call▁end｜&gt;</span><span class="token green">&lt;｜tool▁calls▁end｜&gt;</span><span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span><span class="token green">&lt;｜tool▁output▁begin｜&gt;</span><span class="token green">&lt;｜tool▁output▁end｜&gt;</span>Great! The file compiles without any syntax errors. 

## Summary

I have successfully implemented the fix for the bug in the posix implementation of `django/core/files/locks.py`. The changes made are:

1. **Modified the `lock()` function** (lines 109-114): Wrapped the `fcntl.flock()` call in a try-except block that returns `True` on success and `False` when an `OSError` is raised.

2. **Modified the `unlock()` function** (lines 116-121): Similarly wrapped the `fcntl.flock()` call in a try-except block that returns `True` on success and `False` when an `OSError` is raised.

The fix addresses the core issue described in the PR:
- The original code incorrectly compared the return value of `fcntl.flock()` with 0, but `fcntl.flock()` returns `None` on success and raises an `OSError` on failure
- This meant the functions always returned `False` (`None == 0` is `False`)
- The new implementation properly handles the success/failure cases by using try-except blocks
- This is particularly important for non-blocking locks (`LOCK_NB`) where callers need to know if the lock was successfully acquired

The changes are minimal and focused, exactly matching the suggested fix in the PR description.<span class="token yellow">&lt;｜end▁of▁sentence｜&gt;</span></div>
